Tunnel-confined and quenching-anchored atomic Cu in transition metal oxides for efficient catalytic oxidation

Atomic-level dispersed metal catalysts have garnered considerable attention in heterogeneous catalysis due to their ultrahigh atomic efficiency, exceptional catalytic activity, and well-defined active site structures. However, achieving complete atomic-level dispersion of non-precious metals at high mass loadings on metal oxide supports remains a significant challenge. Here, we report the synthesis of a catalyst with highly dispersed 2.6 wt% Cu species on the tunnel-structured α -MnO 2 (MnO 2 -QCu) via a quenching strategy. This approach synergistically leverages the rapid nucleation characteristic of quenching and the confinement effect of the α -MnO 2 tunnel structure. Beyond the conventional approach to catalyst loading, the activated tunnel structure of α -MnO 2 can provide additional Cu anchoring sites, effectively increasing the number of accessible catalytically active sites. The resulting MnO 2 -QCu exhibits superior activity in CO oxidation, outperforming most reported Mn-based catalysts, and demonstrates excellent durability over 100 h under humid conditions. Mechanistic studies reveal that MnO 2 -QCu facilitates the dual activation of lattice and molecular oxygen, while the resulting Cu-V O -Mn interfaces promote charge transfer and enhance O 2 adsorption and activation, thereby enabling efficient and stable catalytic oxidation. This work offers a general and feasible route to design high-loading single-atom catalysts on oxide supports for energy and environmental applications.